/* Test program for elf_strptr function.
Copyright (C) 2015 Red Hat, Inc.
This file is part of elfutils.
This file is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
elfutils is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include ELFUTILS_HEADER(elf)
#include <gelf.h>
/* Index of last string added. Returned by add_string (). */
static size_t stridx = 0;
/* Some random strings. */
static char *str1;
static size_t str1_off;
static char *str2;
static size_t str2_off;
static char *str3;
static size_t str3_off;
/* First three strings we write out. They should always be there. */
static char *orig_str1;
static size_t orig_str1_off;
static char *orig_str2;
static size_t orig_str2_off;
static char *orig_str3;
static size_t orig_str3_off;
static void
check_orig_strings (Elf *elf, int ndx, const char *msg)
{
printf ("checking orig strings: %s\n", msg);
const char *str = elf_strptr (elf, ndx, 0);
printf ("\t'%s'\n", str);
if (str == NULL || strcmp ("", str) != 0)
exit (1);
str = elf_strptr (elf, ndx, 1);
printf ("\t'%s'\n", str);
if (str == NULL || strcmp (".strings", str) != 0)
exit (1);
str = elf_strptr (elf, ndx, orig_str1_off);
printf ("\t'%s'\n", str);
if (str == NULL || strcmp (orig_str1, str) != 0)
exit (1);
str = elf_strptr (elf, ndx, orig_str2_off);
printf ("\t'%s'\n", str);
if (str == NULL || strcmp (orig_str2, str) != 0)
exit (1);
str = elf_strptr (elf, ndx, orig_str3_off);
printf ("\t'%s'\n", str);
if (str == NULL || strcmp (orig_str3, str) != 0)
exit (1);
}
static void
check_strings (Elf *elf, int ndx, const char *msg)
{
check_orig_strings (elf, ndx, msg);
const char *str = elf_strptr (elf, ndx, str1_off);
printf ("\t'%s'\n", str);
if (str == NULL || strcmp (str1, str) != 0)
exit (1);
str = elf_strptr (elf, ndx, str2_off);
printf ("\t'%s'\n", str);
if (str == NULL || strcmp (str2, str) != 0)
exit (1);
str = elf_strptr (elf, ndx, str3_off);
printf ("\t'%s'\n", str);
if (str == NULL || strcmp (str3, str) != 0)
exit (1);
}
/* Adds a string and returns the offset in the section. */
static size_t
add_string (Elf_Scn *scn, char *str)
{
size_t lastidx = stridx;
size_t size = strlen (str) + 1;
Elf_Data *data = elf_newdata (scn);
if (data == NULL)
{
printf ("cannot create data SHSTRTAB section: %s\n", elf_errmsg (-1));
exit (1);
}
data->d_buf = str;
data->d_type = ELF_T_BYTE;
data->d_size = size;
data->d_align = 1;
data->d_version = EV_CURRENT;
stridx += size;
printf ("add_string: '%s', stridx: %zd, lastidx: %zd\n",
str, stridx, lastidx);
return lastidx;
}
static void
check_elf (const char *fname, int class, int use_mmap)
{
printf ("\nfname: %s\n", fname);
stridx = 0;
int fd = open (fname, O_RDWR | O_CREAT | O_TRUNC, 0666);
if (fd == -1)
{
printf ("cannot open `%s': %s\n", fname, strerror (errno));
exit (1);
}
Elf *elf = elf_begin (fd, use_mmap ? ELF_C_WRITE_MMAP : ELF_C_WRITE, NULL);
if (elf == NULL)
{
printf ("cannot create ELF descriptor: %s\n", elf_errmsg (-1));
exit (1);
}
// Create an ELF header.
if (gelf_newehdr (elf, class) == 0)
{
printf ("cannot create ELF header: %s\n", elf_errmsg (-1));
exit (1);
}
GElf_Ehdr ehdr_mem;
GElf_Ehdr *ehdr = gelf_getehdr (elf, &ehdr_mem);
if (ehdr == NULL)
{
printf ("cannot get ELF header: %s\n", elf_errmsg (-1));
exit (1);
}
// Initialize header.
ehdr->e_ident[EI_DATA] = class == ELFCLASS64 ? ELFDATA2LSB : ELFDATA2MSB;
ehdr->e_ident[EI_OSABI] = ELFOSABI_GNU;
ehdr->e_type = ET_NONE;
ehdr->e_machine = EM_X86_64;
ehdr->e_version = EV_CURRENT;
// Create strings section.
Elf_Scn *scn = elf_newscn (elf);
if (scn == NULL)
{
printf ("cannot create strings section: %s\n", elf_errmsg (-1));
exit (1);
}
// Add an empty string to the table as NUL entry for section zero.
add_string (scn, "");
GElf_Shdr shdr_mem;
GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
if (shdr == NULL)
{
printf ("cannot get header for strings section: %s\n", elf_errmsg (-1));
exit (1);
}
shdr->sh_type = SHT_STRTAB;
shdr->sh_flags = 0;
shdr->sh_addr = 0;
shdr->sh_link = SHN_UNDEF;
shdr->sh_info = SHN_UNDEF;
shdr->sh_addralign = 1;
shdr->sh_entsize = 0;
shdr->sh_name = add_string (scn, ".strings");
// We have to store the section strtab index in the ELF header.
// So sections have actual names.
int ndx = elf_ndxscn (scn);
ehdr->e_shstrndx = ndx;
if (gelf_update_ehdr (elf, ehdr) == 0)
{
printf ("cannot update ELF header: %s\n", elf_errmsg (-1));
exit (1);
}
// Add some random strings. These are the original ones. They should
// always be there (together with the empty "" and .strings section
// name strings.
orig_str1 = "elfutils";
orig_str1_off = add_string (scn, orig_str1);
orig_str2 = "strtabelf";
orig_str2_off = add_string (scn, orig_str2);
orig_str3 = "three";
orig_str3_off = add_string (scn, orig_str3);
// Finished strings section, update the header.
if (gelf_update_shdr (scn, shdr) == 0)
{
printf ("cannot update STRTAB section header: %s\n", elf_errmsg (-1));
exit (1);
}
// Let the library compute the internal structure information.
if (elf_update (elf, ELF_C_NULL) < 0)
{
printf ("failure in elf_update(NULL): %s\n", elf_errmsg (-1));
exit (1);
}
// Check our strings are there.
check_orig_strings (elf, ndx, "first elf_update, before write");
// Write everything to disk.
if (elf_update (elf, ELF_C_WRITE) < 0)
{
printf ("failure in elf_update(WRITE): %s\n", elf_errmsg (-1));
exit (1);
}
// Check out strings are there.
check_orig_strings (elf, ndx, "first elf_update, after write");
// Add some more random strings. These will not be written to disk.
scn = elf_getscn (elf, ndx);
if (scn == NULL)
{
printf ("couldn't re-get strings section: %s\n", elf_errmsg (-1));
exit (1);
}
str1 = "elfutils2";
str1_off = add_string (scn, str1);
str2 = "strtabelf2";
str2_off = add_string (scn, str2);
str3 = "three2";
str3_off = add_string (scn, str3);
// Update internal structure information again.
if (elf_update (elf, ELF_C_NULL) < 0)
{
printf ("failure in re-elf_update(NULL): %s\n", elf_errmsg (-1));
exit (1);
}
// Check our new strings are there.
check_strings (elf, ndx, "first extra strings");
if (elf_end (elf) != 0)
{
printf ("failure in elf_end: %s\n", elf_errmsg (-1));
exit (1);
}
close (fd);
/* Read the ELF from disk now. */
fd = open (fname, O_RDWR, 0666);
if (fd == -1)
{
printf ("cannot open `%s' read-only: %s\n", fname, strerror (errno));
exit (1);
}
elf = elf_begin (fd, use_mmap ? ELF_C_RDWR_MMAP : ELF_C_RDWR, NULL);
if (elf == NULL)
{
printf ("cannot create ELF descriptor read-only: %s\n", elf_errmsg (-1));
exit (1);
}
/* Are our strings there? */
check_orig_strings (elf, ndx, "read ELF file, orig strings");
// Add some more random strings.
scn = elf_getscn (elf, ndx);
if (scn == NULL)
{
printf ("couldn't re-get strings section: %s\n", elf_errmsg (-1));
exit (1);
}
shdr = gelf_getshdr (scn, &shdr_mem);
if (shdr == NULL)
{
printf ("cannot get header for strings section: %s\n", elf_errmsg (-1));
exit (1);
}
// Reset stridx to end of section.
printf ("sh_size: %" PRIu64 "\n", shdr->sh_size);
stridx = shdr->sh_size;
str1 = "0123456789";
str1_off = add_string (scn, str1);
str2 = "supercalifragilisticexpialidocious";
str2_off = add_string (scn, str2);
str3 = "forty-two";
str3_off = add_string (scn, str3);
// Update internal structure information.
if (elf_update (elf, ELF_C_NULL) < 0)
{
printf ("failure in rw-elf_update(NULL): %s\n", elf_errmsg (-1));
exit (1);
}
/* Check our new strings are there. */
check_strings (elf, ndx, "read file, added strings");
// Write updated ELF file.
if (elf_update (elf, ELF_C_WRITE) < 0)
{
printf ("failure in re-elf_update(NULL): %s\n", elf_errmsg (-1));
exit (1);
}
if (elf_end (elf) != 0)
{
printf ("failure in elf_end: %s\n", elf_errmsg (-1));
exit (1);
}
close (fd);
// And read it in one last time.
fd = open (fname, O_RDONLY, 0666);
if (fd == -1)
{
printf ("cannot open `%s' read-only: %s\n", fname, strerror (errno));
exit (1);
}
elf = elf_begin (fd, use_mmap ? ELF_C_READ_MMAP : ELF_C_READ, NULL);
if (elf == NULL)
{
printf ("cannot create ELF descriptor read-only: %s\n", elf_errmsg (-1));
exit (1);
}
/* Are all our strings there? */
check_strings (elf, ndx, "all together now");
if (elf_end (elf) != 0)
{
printf ("failure in elf_end: %s\n", elf_errmsg (-1));
exit (1);
}
close (fd);
unlink (fname);
}
int
main (int argc __attribute__ ((unused)), char *argv[] __attribute__ ((unused)))
{
elf_version (EV_CURRENT);
// Fill holes with something non-zero to more easily spot
// unterminated strings.
elf_fill ('X');
check_elf ("strtab.elf.32", ELFCLASS32, 0);
check_elf ("strtab.elf.32.mmap", ELFCLASS32, 1);
check_elf ("strtab.elf.64", ELFCLASS64, 0);
check_elf ("strtab.elf.64.mmap", ELFCLASS64, 1);
return 0;
}